No such thing as a brontosaurus

Barely a month goes by without a new fossil find that challenges our understanding of how dinosaurs lived. Dan Cossins discovers that everyone's favourite brontosaurus may have just been a cultural myth...

We’re all familiar with the gentle giant of the Jurassic, but the brontosaurus only entered the public consciousness thanks to a case of mistaken identity. The mix-up occurred in the late 19th century, when the race to unearth new dinosaur species in the American West led to slipshod methods and hasty classifications.

In 1877, Othniel Charles Marsh, a distinguished palaeontologist at Yale University, published a description of the excavated bones of a large dinosaur, which he named Apatosaurus ajax.

Two years later, Marsh received 25 crates of bones of another large dinosaur discovered at Como Bluff, Wyoming. Somewhat larger than the previous example, this specimen was far more complete and Marsh identified it as a new genus, Brontosaurus excelsus.

The finds were prepared for the first ever mounted display of a sauropod skeleton, at Yale’s Peabody Museum of Natural History. But there was no head for the brontosaurus, so Marsh improvised, and used the skull of a Brachiosaurus, the only other sauropod for which good skull material was available. Despite the much-publicised debut of brontosaurus, another palaeontologist, Elmer Riggs, argued in 1903 that brontosaurus was not sufficiently different to warrant its own genus.

Apatosaurus was merely a juvenile version of brontosaurus – and the former had priority because it was named first.

So that was that. The correct head was finally mounted on an Apatosaurus skeleton at the Carnegie Museum in 1979, but the name brontosaurus persisted long after it had been abandoned by science. As late as 1989 the US Post Office issued a stamp with the name brontosaurus, which to this day lumbers on in the public imagination.